Lead screw drive mechanism



March 12, 1968 w. J. BARRON 3,372,618

LEAD SCREW DRIVE MECHANISM Filed Jan. 18, 1966 United States PatentFiled Jan. 18, 1966, Ser. No. 521,309 Claims. (Cl. 9013.3)

The present invention relates to a lead screw drive mechanism fordriving a pair of carriages both of which are mounted on a common leadscrew which is rotatable to advance the carriages. The invention relatesin particular to apparatus for releasably interconnecting a pair of suchcarriages so that upon rotation of the common lead screw the carriagesmay either be advanced in the same axial direction or in oppositedirections as required in any given application.

The lead screw drive mechanism of the present invention will bedescribed herein in conjunction with an electronic engraving machine,although it will be understood that it may have other like applicationswhere a pair of carriages are mounted on a common lead screw and it isdesired to advance such carriages either in the same direction or inopposite directions. An electronic engraving machine of the typereferred to above may comprise a scanning cylinder on which a photographor other copy is mounted, an engraving cylinder on which a metal orplastic plate to be engraved is mounted, a cutter for engraving theplate, and scanning apparatus for sensing the light reflected from thecopy and transmitting electrical impulses proportional thereto thecutter apparatus, whereby upon rotation of the scanning and engravingcylinders and simultaneous axial advancement of the scanner and cutteralong their respective cylinders, the plate will be engraved with linesvarying in width in accordance with the tones of the copy.

Where it is desired to produce an engraved metal or plastic printingplate directly from copy, the engraved plate must be wrong reading inorder that the subject matter reproduced by the engraved plate in asubsequent printing operation will be right reading. Accordingly, inorder that the engraved plate will be wrong reading, the cuttingapparatus and the scanning apparatus must be moved in oppositedirections along their respective scanning and cutting cylinders. Onemethod for etiecting such movement is to mount two carriages on a commonlead screw which is oppositely threaded at its two ends, whereby uponrotation of the lead screw the two carriages,

.one carrying the cutter apparatus and the other carrying the scanningapparatus, will be moved in opposite directions along the lead screw.However, such a lead screw drive cannot be utilized in the foregoingmanner where it is desired to produce a right reading engraving directlyfrom copy. That is, in the manufacture of engraved wall plaques orscrolls or the like which must be right reading, it is necessary thatthe carriage carrying the cutter and the carriage carrying the scanningapparatus be moved in the same axial direction.

It is therefore an object of the present invention to provide animproved carriage drive mechanism which can be utilized to drive a pairof carriages either in the same direction or in opposite directions asis desired for a given application.

The foregoing and other objects and advantages of the invention will beapparent from the following description thereof.

Now in order to acquaint those skilled in the art with the manner ofutilizing and practicing my invention, I shall describe, in conjunctionwith the accompanying drawing, a preferred embodiment of the invention.

In the drawings:

FIGURE 1 is a perspective view of the front portion of an electronicengraving machine equipped with carriage drive mechanism in accordancewith the present invention; and

FIGURE 2 is an enlarged exploded perspective view showing a connectingrod and associated bracket means for interconnecting a pair of carriagemembers so as to permit one carriage to advance the other in accordancewith the present invention.

Referring now to the drawings, there is shown an electronic engravingmachine comprising a base 20, a cylinder shaft 22, an engraving cylinder24, a cutter carriage 26, a cutter head 28, a scanning cylinder 30, ascanner carriage 32, a scanner 34, motor means 36, a lead screw 38, ahousing 40 which encloses a ratchet advance mechanism for connecting themotor means 36 to the lead screw 38, and thrust bearing means 42 forsupporting the lead screw 38. The motor means 36 rotates the shaft 22and the cylinders 24 and 30 mounted thereon, and the ratchet mechanism(not shown) disposed within the housing 40 is util'ued to connect themotor to the lead screw 38 for intermittent rotation of the lead screwin one direction. The lead screw 38 has oppositely formed threads at itstwo ends 38a and 38b whereby upon rotation in the direction it is drivenby the motor 36 it will advance the cutter carriage 26 and the scannercarriage 32 towards one another. In this manner, the scanner 34 willscan copy mounted on the scanning cylinder 30 and transmit electricalimpulses to the cutter head 28 for engraving a plate mounted on theengraving cylinder 24. For a more complete description of an electronicengraving machine of the foregoing type, reference may be had to my US.Patent 3,183,745, issued May 18, 1965, and assigned to the assignee ofthe present invention.

The cutter carriage 26 has a manually operable lever or handle 44thereon for controlling engagement of the carriage with the lead screw38, and a similar manually operable control lever 46 is provided on thescanner carriage 32. Accordingly, when the two levers 44 and 46 are bothin their down or operative positions, such as shown with respect to thelever 44 in FIGURE 1, then both of the carriages 26 and 32 will beoperatively engaged with the lead screw 38, in particular with therespective oppositely threaded end portions 38a and 3% thereof. Thus,rotation of the lead screw by the motor 36 and associated ratchetmechanism 40 will advance the two carriages toward one another. Eitherof the carriages 26 and 32 may be disengaged from the lead screw 38 bymoving the corresponding control lever to an upper inoperative position,as shown for example with respect to the control lever 46 in FIGURE 1.

In accordance with the present invention, a connecting rod 48 isprovided for interconnecting the two carriages 26 and 32 in order thatone carriage may drive the other. Thus, a mounting bracket 50 is screwedor otherwise fixedly secured to the top of the carriage 26, and thebracket 50 is provided with a pair of spaced apart upwardly extendinglugs 52 and 54 having aligned horizontal mounting holes 56 and 58 formedtherein respectively for receiving the ends of a mounting pin 60. Oneend of the connecting rod 48 has a transverse hole 62 formed therein,and the pin 60 is positioned so as to pass through the aperture 62 withits ends disposed in the lug mounting holes 56 and 58, whereby the oneend of the rod 48 is pivotally supported at the mounting bracket 50.

A second mounting bracket 64 is screwed or otherwise securely fastenedto the top of the scanner carriage 32, and the bracket 64 includes anupright mounting post 66 having a horizontal bore 68 formed therein forreceiving the right hand end of the connecting rod 48. In addition, aset screw 70 is threaded downwardly into the top of the post 66 so as tocommunicate with the bore 68. In this manner, when the end of the rod 48is positioned in the bore 68, the set screw 70 may be utilized to clampdown on the rod and lock the same in position. It will be noted that thecarriage 26 further includes a conventional hand wheel 72, and thecarriage 32 includes a similar hand wheel 74, such hand wheels beingmanually operable to move the respective carriages in any desireddirection when they are disengaged from the lead screw 38. Thus, one orboth of the hand wheels may be manually operated in order to positionthe carriages when the connecting rod 48 is being operatively secured tothe right hand bracket member 64.

It will be understood from the foregoing that when it is desired tooperate the engraving machine so that the two carriages 26 and 32 willadvance in the same direction, one of the carriages, for example thescanner carriage 32, is disengaged from the lead screw 38 by moving thelever 46 to its upper inoperative position as shown in FIGURE 1. Theconnecting rod 48 is then pivoted to a horizontal position, and bymanipulating the hand wheel 74 so as to manually advance the carriage 32toward the carriage 26, the right hand end of the rod 48 is caused toproject through the bore 68 in the mounting post 66. It will benecessary to position the two carriages 26 and 32 at varying distancesapart depending upon the particular engraving job to be performed, butonce the carriages are spaced apart as desired with the right hand endof the rod 48 extending through the bore 68 in the post 66, the setscrew 70 is tightened to lock the end of the rod in position and therebyrigidly interconnect the carriages.

In the example being described, lever 44 associated with the cuttercarriage 26 may be left in its downward or operative position so thatthe latter carriage is engaged with the lead screw 38. Accordingly, whenthe lead screw is rotated so as to move the cutter carriage 26 to theright, the carriage 26 will act through the connecting rod 38 to pushthe scanner carriage 32 to the right. In the particular machine beingdescribed herein the motor 36 and ratchet mechanism 49 are adapted torotate the lead screw 38 in only one direction. However, various drivemeans may be utilized for driving the lead screw in either direction,and it will be understood that in whichever direction the carriage 26 isdriven, the latter will act through the rod 48 to move the othercarriage 32 in the same direction. Moreover, by moving the lever 44 toits disengaged position and moving the lever 46 to its engaged position,the lead screw 38 will drive the right hand carriage 32 which in turnwill act through the rod 48 to move the carriage 26 in the samedirection. When it is desired to have the two carriages 26 and 32advance in opposite directions, both levers 4-4 and 46 are moved totheir engaged positions and the set screw 70 is loosened so as todisengage the end of the rod 48 from the supporting post 66. When not inuse, the rod 48 may simply be pivoted in a counterclockwise direction toan out of the way position, while remaining pivotally connected to thebracket 50 so as to be readily available for use when desired.

While I have described my invention in a preferred form, I do not intendto be limited to such form, except insofar as the appended claims are solimited, since modifications coming within the scope of my inventionwill readily occur to others, particularly with my disclosure beforethem.

I claim:

1. In an engraving machine of the type having a cutter carriage and ascanner carriage mounted on a common lead screw which is oppositelythreaded at its two 4 ends for advancing said carriages inoppositedirections upon rotation of said screw, and manual control means on eachcarriage for selectively engaging and disengaging the same with saidlead screw, the improvement comprising, in combination, first mountingmeans on one of said carriages, second mounting means on the other ofsaid carriages, and a rigid connecting member extending between saidfirst and second mounting means, one end of said connecting member beingsecured to said first mounting means, and the other end of saidconnecting member being releasably secured to said second mountingmeans, whereby upon engagement of a selected one and disengagement ofthe other of said manual control means and rotation of said lead screwthe engaged one of said carriages will be advanced by said lead screwand will act through said rigid connecting member to advance the otherof said carriages in the same direction.

2. The invention of claim 1 wherein said second mounting means isadjustable relative to said other end of said connecting member topermit adjustment of the spacing between the two connected carriages.

3. The invention of claim 1 wherein said one end of said connectingmember is pivotally secured to said first mounting means whereby whennot in use said other end may be released from said second mountingmeans and said connecting member pivoted to a storage position whileremaining secured to said first mounting means.

4-. In an engraving machine of the type having a cutter carriage and ascanner carriage mounted on a common lead screw which is oppositelythreaded at its two ends for advancing said carriages in oppositedirections upon rotation of said screw, and manual control means on eachcarriage for selectively engaging and disengaging the same with saidlead screw, the improvement comprising, in combination, first mountingmeans including pivot pin means on one of said carriages, secondmounting means including releasable clamping means on the other of saidcarriages, and a rigid connecting member extending between said firstand second mounting means, one end of said connecting member beingpivotally secured to said first mounting means by said pivot pin means,and the other end of said connecting member being releasably secured tosaid second mounting means by said clamping means, said second mountingmeans being adjustable relative to said other end of said connectingmember to permit adjustment of the spacing between the two connectedcarriages, whereby upon engagement of a selected one and disengagementof the other of said manual control means and rotation of said leadscrew the engaged one of said carriages will be advanced by said leadscrew and will act through said rigid connecting member to advance theother of said carriages in the same direction.

No references cited LEONIDAS VLACHOS, Primaiy Examiner.

1. IN AN ENGRAVING MACHINE OF THE TYPE HAVING A CUTTER CARRIAGE AND ASCANNER CARRIAGE MOUNTED ON A COMMON LEAD SCREW WHICH IS OPPOSITELYTHREADED AT ITS TWO ENDS FOR ADVANCING SAID CARRIAGES IN OPPOSITEDIRECTIONS UPON ROTATION OF SAID SCREW, AND MANUAL CONTROL MEANS ON EACHCARRIAGE FOR SELECTIVELY ENGAGING AND DISENGAGING THE SAME WITH SAIDLEAD SCREW, THE IMPROVEMENT COMPRISING, IN COMBINATION, FIRST MOUNTINGMEANS ON ONE OF SAID CARRIAGES, SECOND MOUNTING MEANS ON THE OTHER OFSAID CARRIAGES, AND A RIGID CONNECTING MEMBER EXTENDING BETWEEN SAIDFIRST AND SECOND MOUNTING MEANS, ONE END OF SAID CONNECTING MEMBER BEINGSECURED TO SAID FIRST MOUNTING MEANS, AND THE OTHER END OF SAIDCONNECTING MEMBER BEING RELEASABLY SECURED TO SAID SECOND MOUNTINGMEANS, WHEREBY UPON ENGAGEMENT OF A SELECTED ONE AND DISENGAGEMENT OFTHE OTHER OF SAID MANUAL CONTROL MEANS AND ROTATION OF SAID LEAD SCREWTHE ENGAGED ONE OF SAID CARRIAGES WILL BE ADVANCED BY SAID LEAD SCREWAND WILL ACT THROUGH SAID RIGID CONNECTING MEMBER TO ADVANCE THE OTHEROF SAID CARRIAGES IN THE SAME DIRECTION.